Topical coating applying apparatus and methods

ABSTRACT

An enrober (100) for applying a topical coating to an exterior surface of multiple pieces of a food base is disclosed having a marked decrease in the amount of build-up upon the internal surface of the drum (102) allowing for reductions in cleaning service requirements and its concomitant losses in production capacity and for reductions in undesirable product agglomerates. In the preferred form, the drum (102) is formed by a thin wall in a generally cylindrical shape and formed of hydrophobic material in the form of high-density polyethylene having low-stick characteristics with the topically coated food base. Moisture, in addition to any present in the topical coating, is added to the drum (102) to prevent or practically eliminate build-up on the drum (102). The topical coating in the form of a slurry can be co-sprayed with steam in an atomized intermixed spray onto the food base by a nozzle (10, 80). Also, a renewable barrier between the continuous inner surface of the drum (102) and the food base can be formed by spraying water or steam by nozzles (116) as a thin film of water onto the inner surface of the drum (102) above the food base.

CROSS REFERENCE

The present application is a continuation-in-part of U.S. applicationSer. No. 08/259,709 filed Jun. 14, 1994, now U.S. Pat. No. 5,453,383.

1. Field of the Invention

The present invention is directed to a food processing apparatus andmethods of using such apparatus. More particularly, the presentinvention is directed to an improved apparatus for applying a topicalcoating such as a sugar coating solution to a Ready-To-Eat breakfastcereal base using a secondary source of moisture and a plastic drum.

2. Background of the Invention

A wide variety of operations, especially food processing, involve theapplication of a fluid coating material. In particular, the preparationof certain presweetened Ready-To-Eat ("R-T-E") breakfast cerealsinvolves the application of a sticky sugar coating solution or slurry toa prepared R-T-E cereal base. The wet, sugar coated R-T-E cereal issubsequently dried and packaged to form the finished product.

Conventionally, the sugar coating solution or slurry is applied to theR-T-E cereal base with conventional spray nozzles that dispense theslurry in a spray pattern using only the hydrostatic pressure of theslurry supply to form the spray. The nozzles are typically mountedwithin an R-T-E cereal base enrober. A good description of such coatingapparatus and techniques is given in "Breakfast Cereals and How They AreMade" (edited by R. B. Fast and E. F. Caldwell), American Association ofCereal Chemists, Inc., 1990, pg. 200-220. Such an enrober is anapparatus having a rotating horizontally extending vessel or drum,generally cylindrically shaped, although the axis may be at a slightangle relative to the horizontal, frequently having a lower dischargeend. The cereal base is fed at one end and is discharged at the oppositeend. As the vessel rotates and as the slurry is dispensed within theenrober, the slurry is evenly applied, more or less, as the cereal istumbled within and travels along the axis of the enrober. While usefuland effective, the ease of conventional hydrostatic slurry restrictiveorifice discharge nozzles has numerous disadvantages.

One disadvantage involves the gradual build-up of the slurry upon theinterior of the enrober vessel. After this build-up of sugar, theenrober must be thoroughly cleaned. Depending upon a variety of factors,the cleaning operation must be conducted at least once per day andperhaps as frequently as once per operating shift. Cleaning the enroberis thus a standard element of operating hygiene that usually takes up toan hour to perform. Thus, slurry build-up requires the direct cost ofmaintenance servicing. More importantly, since most cereal processinglines are generally continuous, slurry build-up can cause the moresignificant cost of downtime of the entire cereal processing line.

Still another problem with the use of conventional restrictive orificenozzles involves the evenness of the slurry distribution over the cerealbase. Of course, an evenly distributed slurry is desired. Usingconventional nozzles, improved evenness of distribution can be obtainedby greater tumbling (e.g., faster rotation and/or increased residencetime in the enrober). However, many R-T-E cereals, especially those inflake form, are fragile. Greater tumbling leads to the development ofbroken flakes or fines that subsequently must be screened out. Finesgeneration can lead to yield losses of up to 5% or more of the cerealline's capacity.

Still another problem is undesirable product agglomeration. Undesirableproduct agglomeration can be aggravated by poor slurry distribution.Undesirable product agglomeration can result in the generation of large,unattractive, hard pieces that should be screened out.

Still another benefit resides in the reduction in the amount ofexpensive sugar ingredients lost as part of the sugar build-up that mustbe washed away during enrober cleaning. Still another advantage residesin reduction in undesirable product agglomerates.

Surprisingly, dramatic improvements in the sugar solution coating ofR-T-E cereal has been obtained utilizing an enrober including a drumhaving a hydrophobic material internal surface, steam assisted slurrynozzles and/or an air atomized, drum spray system. One benefit is amarked decrease in the amount of sugar build-up upon the enrober'sinterior surface that allows for reductions in cleaning servicerequirements and its concomitant losses in production capacity.

Still another advantage resides in reduction in undesirable productagglomerates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view taken along lines 1--1 of FIG. 2 of afirst embodiment of the present steam nozzle.

FIG. 2 is an end view of the steam nozzle showing the discharge end.

FIG. 3 is an opposed end view of the steam nozzle showing the inlet end.

FIG. 4 is a sectional exploded view of the nozzle with the boltsremoved.

FIG. 5 is a cross sectional view taken along lines 5--5 of FIG. 1showing the interior surface of the discharge cap.

FIG. 6 is a cross sectional view of the end cap taken along lines 6--6of FIG. 5.

FIG. 7 is a cross sectional view taken along lines 7--7 of FIG. 8 of asecond preferred embodiment of the present steam nozzle.

FIG. 8 is an end view of the steam nozzle showing the discharge cap.

FIG. 9 is an opposed end view of the steam nozzle showing the inlet end.

FIG. 10 is a sectional exploded view of the steam nozzle.

FIG. 11 is a cross sectional view of the end cap taken along lines11--11 of FIG. 7.

FIG. 12 is a diagrammatic side view of an enrober according to thepreferred teachings of the present invention, with portions broken awayto show internal construction.

FIG. 13 is a cross sectional view of the enrober of FIG. 12 taken alonglines 13--13 of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An enrober according to the preferred teachings of the present inventionis shown in the drawings and generally designated 100. Generally,enrober 100 includes a rotating, tumbling vessel or drum 102 which inthe most preferred form is generally cylindrically shaped. Drum 102 isgenerally horizontal, although the axis may be at a slight anglerelative to the horizontal. Dry base product to be coated is fed in oneend of drum 102 such as by a delivery tube 104 and is discharged at theopposite end 106, which is frequently at a lower vertical position thanthe end of drum 102 including delivery tube 104. Drum 102 is rotated inany desired manner such as by two trunion rings 108 attached to theouter periphery of drum 102. The cylindrical, continuous internalsurface of drum 102 is generally of two styles for differing cerealtypes such as for puff or flake cereals. With puff products, theinternal surface is smooth whereas for flake products, the internalsurface includes a plurality of circumferentially spaced, axiallyextending flights or lifters 110 which pick-up the cereal pieces insideof drum 102 to flip them over during rotation of drum 102. Thus, lifters110 aid in inducing a tumbling action of the food product pieces, whichin turn aids in the transfer of the topical coatings from piece-to-piecedue to the pieces rubbing together.

Enrober 100 further includes a dispenser 112 for the topical coatings.Dispenser 112 includes a wand support structure 114 which extendsaxially through either of the ends of drum 102 and radially spacedinward of the internal surface of drum 102. Nozzles 10 can be supportedon structure 114 for spraying the topical coating in a liquid state.

In a first aspect, the invention generally resides in and providesimproved sugar slurry spray nozzles 10 that additionally include a meansfor co-spraying a steam spray to intermix with the sugar slurry sprayexterior to nozzle 10. Referring now to FIG. 1 which shows a firstembodiment of the present steam nozzle 10, nozzle 10 comprises a meansfor spraying a sugar slurry to form a sugar slurry spray pattern and ameans for co-spraying steam into a steam spray pattern into the sugarslurry spray pattern to intermix the sugar slurry spray and steam spray.Specifically, in the preferred embodiment, the nozzle 10 includes anozzle body 12 that can be of any shape but which is convenientlycylindrical. The nozzle body 12 includes and the steam spray means cancomprise an axially extending interior cavity defining a steam chamberor manifold 14, an inlet or receiving end 16 having an inlet end face,and a discharge end 18 having a discharge end face and open to the steamchamber 14. The body 12 additionally comprises at least one means forsupplying a sugar slurry fluid such as an axially aligned slurrydelivery member 22 having a passageway therethrough such as a tubedisposed within an axially aligned bore 20 for receiving tube 22. Thenozzle 10 additionally includes a steam supply 24 which can include asteam supply tube 26 screwed into receiving threads 27 of a steam inletport 28 to provide steam continuously to the steam manifold 14. Theslurry delivery tube 22 is operatively connected to a sugar coatingsupply (not shown) that continuously supplies the sugar slurry undermodest hydrostatic pressure such as a positive displacement pump.

FIGS. 1 and 3 further show that the nozzle 10 further includes at itsreceiving end a means for securing the sugar slurry tube 22 againstlateral movement including a first inlet cap 29 and a first stop head 30that abuts against a first matching shoulder 32 formed in the bore 20.As seen in FIG. 1, the nozzle 10 additionally comprises a seal means forsealing the nozzle against premature steam/slurry intermix or loss ofsteam at the receiving end 16 as well as from slurry leaking into thesteam cavity including a second or seal head 34 including a conventional"O" ring 36 seated against a matching second shoulder 38 in the axialbore 20. The inlet cap 29 is secured in place in conventional mannersuch as by a plurality of screws (e.g., four or six) 42 through bores 40in the inlet cap 29 which are screwed into threaded screw hole bores 44in the nozzle body 12. The inlet cap 29 includes its own axial bore 48having threads for receiving a slurry inlet supply tube 23.

Referring now to FIG. 2, it is seen that the nozzle 10 further includesa second, discharge end means for securing the sugar slurry supply tubeagainst lateral movement and for closing the opening in discharge end 18to steam chamber 14 such as a discharge cap 60 having an exteriordischarge face 61 secured in any conventional manner to the dischargeend 18 of the nozzle body 12 such as by a plurality, (e.g., four) screws62 through bores 63 into receiving threaded bores 65 in the nozzle body12. Discharge cap 60 includes a central aperture 64 for receiving theslurry delivery tube 22. Additionally, the discharge cap 60 furtherincludes at least one steam discharge orifice from the steam chamber 14positioned proximate the central aperture 64 for the slurry dischargetube 22 such as the opposed pair of arcuate or crescent shaped slits 66and 68.

In preferred embodiments, the steam discharge slits 66 and 68 and theslurry tube discharge end orifice 25 are co-planar, i.e., flat with theplane of the cap's discharge face 61, for improved spray patterndistribution and cleanliness. In other embodiments, either the slits orthe discharge orifice 25 are recessed or extended beyond the capdischarge face 61.

The slits in highly preferred embodiments each comprise about 30° to70°, preferably about 45° of arc spaced equally around aperture 64.While two slits are depicted, other arrangements, e.g., additional slitsor holes, can also be employed. The slits are seen to have a width whichpreferably can range from about 0.25 mm to 1.5 mm and a length ofpreferably about 5 to 15 mm.

The shape and placement of the slits importantly cause the slurry to beintimately mixed with steam external to the nozzle 10 immediately uponexiting of the nozzle 10 causing, it is believed, the slurry to beatomized into a spray of very fine droplets.

An advantage of this first embodiment is that the angle of dispersion ofthe slurry spray is low or even close to zero which allows for the sprayto be focused in those applications that require careful control orplacement of the spray. Also, the steam exit vector is co-axial with theslurry exit vector which avoids excessively turbulent mixing.

Reference now is made briefly to FIG. 4 which shows the above describednozzle components in an exploded view.

Reference now is made to FIGS. 5 and 6 which show the interior surface70 of discharge cap 60. FIG. 6 shows that the interior surface 70 ispreferably fabricated with shallow fan cuts 72 and 74 proximate eachsteam slit 66 and 68 for guiding the steam as it exits from the steamreservoir. The fan cuts are deepest as they terminate in the arcuateslit and are progressively shallower as the fan cut extends outwardlyfrom the center. The fan cut(s) assists in the development of an evenlyshaped cone pattern to the slurry spray and minimizes condensatebuild-up. The inner surface 70 of the cap 60 includes a shallow (e.g.,15° to 20°) frusto-conical cut 76 for directing the steam to the arcslits 66 and 68.

In order to change the rate of flow of the steam, a simple valveupstream is opened/closed to regulate steam flow rates.

In the present nozzle design, regulation of the coating solution flowrates can be accomplished simply by substituting one slurry deliverytube 22 having a larger or smaller inner diameter as desired. Anadvantage of the present nozzle design is that such a substitution iseasily made by removing the retaining inlet cap and substituting a tube22 having a different, desired size internal diameter ("ID"). The flarednozzle insert is characterized by an inner diameter opening size. Thenozzle insert is simply substituted with a nozzle insert having adifferent, desired size ID. By adjusting the output of the coatingsolution by using differently sized inserts, the shape of the steamoutlet remains the same and thus relatively easy to control.

Reference is now made to FIGS. 7-11 which show a second, preferredembodiment similar in most aspects to the first embodiment andcharacterized in that the nozzle 80 is provided with a flared slurrydelivery tube for a wider spray pattern. As can be seen, the basicconfiguration of nozzle 80 is similar to that described for nozzle 10.However, in this embodiment, FIG. 7 shows that the slurry delivery tubeincludes a flared outlet portion 82. In the more highly preferredembodiment depicted, the flared outlet portion 82 is oval in shaperather than a less preferred circular shape. The oval shape of theflared outlet imparts an oval pattern to the discharge spray while acircular shape imparts a cone spray. An oval spray pattern or cone ispreferred to fan spray since fan sprays tend to get a heavier spray loadin the ends of the pattern rather than at the middle.

Reference is now made to FIG. 8 which shows that another feature of theoval shape is that the steam discharge arcuate slits begin to curvearound the edge of the coating spray. Such a construction importantlyminimizes the tendency of the coating spray to form a mist. Therelatively larger slits also even out the distribution of the coatingspray without causing misting. Misting is a problem to be avoided sincethe mist tends to travel and drift. Rather than being applied to thesurface of the R-T-E cereal as desired, misting causes coating solutionloss and undesirable coating solution building on processing equipment.

Reference is now made to FIG. 11 which shows the interior surface 90 ofdischarge cap 88. FIG. 11 shows clearly that the aperture 92 is oval inshape to receive the flared end of the flared slurry discharge tube.

An advantage of the second embodiment having the flared ended supplytube is that the angle of dispersion of the slurry spray is quite high(e.g., 120° for the embodiment depicted) leading to a higher extent ofdispersion which can be particularly desirable when large amounts ofsugar coating are applied to the cereal base.

Conveniently, the second nozzle embodiment can be rapidly adjusted tomodify the amount of slurry to be applied by substituting a dischargeslurry tube having a lower or greater internal diameter as desiredsimilar to that for the first embodiment.

In a minor variation, either embodiment can additionally include asecond fluid supply member if more than one coating fluid is desired tobe applied. For example, one supply may be for a sugar syrup while asecond may supply an edible oil or other fluid.

While the nozzles 10 and 80 can be used in a wide variety of coatingequipment, in a preferred embodiment, the nozzles 10 and 80 are mountedin cereal enrober 100 including rotating drum 102 in substitution forconventional hydrostatically operated nozzles. Nozzles 10 and 80 aredirected towards the product bed and more preferably towards the fastestmoving portion of the product bed, i.e. near the top. Of course, therelative position of the product bed will vary depending upon therotational direction of enrober 100. Specifically, the product willtravel up the internal surface of drum 102 due to its rotation beforefalling back, with the product bed extending from between about the fiveto nine o'clock positions for clockwise rotation and from between aboutthe seven to three o'clock positions for counterclockwise rotation inthe preferred form.

In other aspects of the present invention, the invention generallyresides in and provides a moisture film on the cylindrical internalsurface of drum 102 and specifically intermediate the cylindricalinternal surface of drum 102 and the food product being tumbled inside.Specifically, in the preferred embodiment, a plurality of axiallyspaced, atomizing water spray nozzles 116 are mounted to supportstructure 114 for spraying atomized water onto the cylindrical internalsurface of drum 102 at a location above the food product being tumbledinside. It has been found that the position where the water is sprayedon drum 102 is not critical as long as it is above the food product bedsuch that it engages and covers the cylindrical internal surface of drum102. Nozzles 116 should be selected to provide a wide, fine spraypattern at very small flow rates. Nozzles 116 in the most preferred formare Spraying System Nozzles model 11005-1/4 J-SS with spray set upnumber SU13-SS.

Air pressure to nozzles 116 in the preferred form is controlled by oneregulator for all nozzles 116 and is set from 10-25 psig (60-150 KPa)with a flow around 2 standard cubic feet (0.05663 cubic meters) perminute per nozzle 116. In the most preferred form, water pressure toeach nozzle 116 is controlled by individual water regulators which arenormally set from 5-15 psig (30-90 KPa) with a flow of 0.7 to 1 gallons(2.65 to 3.785 liters) per hour per nozzle 116 depending on theparticular enrober 100 and which product is being topically coated. Itcan then be appreciated that water flow can be adjusted for differentaxial lengths along drum 102 according to the preferred teachings of thepresent invention. For example, the nozzle(s) 116 in the area wheretopical coatings in the form of particulates are dispensed can beadjusted to increase water flow to keep the particulates from stickingto drum 102, with particulates traditionally posing difficult build-upproblems. Water can be supplied from conventional sources such asdirectly off a city water header, but it is recommended that the waterbe filtered to prevent plugging of nozzles 116.

Water sprayed by nozzles 116 can be hot or cold, with temperature notseeming to be a factor in operation. In this regard, water could besprayed on the cylindrical internal surface of drum 102 in the form ofsteam sprayed by nozzles 116 instead of water and compressed air.However, steam in specific applications is less preferred for safety andcontrol reasons. Specifically, steam involves using very hot supplylines to which the operator is exposed especially when makingadjustments. Further, especially at low flow rates according to thepresent invention, steam is hard to control. Also, excessive moisturebuild-up can occur due to steam condensation while nozzles 116 are coldduring initial coming up.

In still other aspects of the present invention, the invention generallyresides in the material forming the internal surface of drum 102.Specifically, in the preferred embodiment, drum 102 is formed of amaterial of a hydrophobic nature. Since the slurry is a water-basedsolution, drums 102 having at least an internal surface formed ofhydrophobic materials help prevent build-up. Further, in the mostpreferred form, drum 102 is formed of a plastic having a low coefficientof friction at the cylindrical internal surface of drum 102 providinglow-stick characteristics relative to the build-up of topical coatingsand product therein. Due to these hydrophobic and low-stickcharacteristics, build-up problems on the cylindrical internal surfaceof drum 102 are virtually eliminated. In the event of build-up requiringcleaning, drum 102 is extremely quick and easy to clean. Specifically,it has been found that only 15 minutes are required to wash clean drum102 according to the present invention using a high-pressure, hot-waterhose, whereas previously 1-3 hours were required to scrape clean drums102 as conventionally formed from steel.

In the preferred form of the present invention, drum 102 is formed ofmolded high-density polyethylene (HDPE). Although the use of ultra-highmolecular weight polyethylene (UHMW) has been previously suggested foruse in nonconventionally shaped enrobers, its use in enrobers 100according to the teachings of the present invention was not possible.Further, although UHMW and HDPE are in the same polyethylene familyhaving very similar mechanical properties, the use according to theteachings of the present invention of HDPE produces surprising,unexpected results when utilized in drum 102 having a generallycylindrical internal surface of the type of the preferred embodimentbecause of some subtle differences. Specifically, these key differencesin mechanical properties between HDPE and UHMW include: tensilestrength, percent of elongation, and continuous duty operatingtemperature. On average, the tensile strength of HDPE is approximately43% higher than UHMW. This allows drum 102 to be much stronger and thusmore durable. The HDPE will not be as susceptible to shock loads orstress failures. Also, the percent of elongation of HDPE is much lowerthan UHMW, providing for a more dimensional stable drum 102 for use invarying environmental conditions. This implies that the HDPE will notshrink and expand as drastically as UHMW, thus making it lesssusceptible to stress or fatigue failure. Further, the thermal capacityof HDPE is much higher than UHMW. HDPE is capable of continuousoperation in an environment up to 250° F. (120° C.), while UHMW is onlyfunctional for continuous duty up to 120° F. (50° C.) (with 180° F. (82°C.) being the threshold where breakdown of mechanical propertiesbegins). Finally, UHMW is typically commercialized in sheets makingformation by molding more difficult.

The significance of these differences concerns the temperature of thetopical coating upon application to the food base. Of course, thetemperature at which all the sugar in a solution is dissolved willincrease as the percentage of solids is increased. Sugar syrups utilizedas topical coatings having about 10%-12% moisture will have total solidsdissolved at about 250° F. (120° C.). Total dissolution of solids isimportant to minimization of a frosted appearance which can occur uponsubsequent drying when undissolved solids act as nuclei for crystalformation. This is why the topical coating even though held at hightemperatures undergoes a final heating step immediately prior toapplication onto the food base. Even with only 10%-12% moisture in thetopical coating, the coated food base generally requires a final dryingstep to remove this moisture. It would be desirable to utilize an evenlower moisture topical coating so as to eliminate the need for the finaldrying step (the food base would be adjusted slightly with regard to itsmoisture content such that upon equilibrium the finished product wouldhave an equivalent moisture). Going to a lower moisture topical coatingwould mean that the application temperature of the topical coating wouldnecessarily be even higher than at the 10% moisture level. Thus, thetensile strength and operating temperature condition of drum 102 iscritical to minimization of subsequent drying.

In the most preferred form of the present invention, drum 102 is formedof a thin wall in a generally cylindrical shape to form the continuouscylindrical internal surface. In the most preferred form, lifters 110are integrally formed by bending the thin wall forming drum 102 todivide drum 102 into a plurality of circumferentially spaced arcuateportions 118 interconnected together by lifters 110. In the preferredform, lifters 110 generally include a first axially extending leg 120having a first axially extending edge integrally connected to thetrailing edge of arcuate portion 118 and a second axially extendingedge. Lifters 110 further include a second axially extending leg 122having a first axially extending edge integrally connected to the secondaxially extending edge of leg 120 and a second axially extending edgeintegrally connected to the leading axially extending edge of the nextcircumferentially adjacent arcuate portion 118. The trailing edges ofarcuate portions 118 and the first axially extending edges of legs 120are circumferentially spaced from and parallel to the leading edges ofarcuate portions 118 and the second axially extending edges of legs 122.Leg 120 extends generally perpendicular to leg 122 and has a widthbetween its first and second axially extending edges which is less thanone-half of the width between the first and second axially extendingedges of leg 122 and specifically is 40% of the width between the firstand second axially extending edges of leg 122. The circumferential widthbetween the leading and trailing edges of arcuate portions 118 is amultiple and in the most preferred form is slightly less than 4 timesthe circumferential width between the first axially extending edge ofleg 120 and the second axially extending edge of leg 120. Rotation ofdrum 102 is in a direction that the leading edges of arcuate portions118 proceed the trailing edges such that legs 120 present abutment areasextending approximately 25° from radial and legs 122 present slide areasfor gently sliding the food pieces to the next arcuate portion 118. Inthe most preferred form, drum 102 has a wall thickness of 0.50 inches(1.27 cm).

OPERATION OF THE INVENTION

In its method aspect, nozzles 10 and 80 co-spray at least one coatingfluid onto a food substrate with steam to form an atomized intermixingspray of coating solution and steam onto a food base. The methods findparticular suitability for use in connection with the sugar coating ofan R-T-E cereal. While the R-T-E cereal base can comprise a puffedcereal, a shred cereal, a biscuit, and the like, the present methods areespecially useful for R-T-E cereal base in the form of flakes. Incertain preferred embodiments, the present methods are practicedemploying nozzles 10 and 80 to provide advantages in terms of ability toadjust and control solution application features such as flow rate andspray pattern through simple and convenient interchange of nozzlepieces.

If desired, a second or additional coating fluid can also besimultaneously supplied along with the sugar slurry, e.g., a vitaminsupply, so as to minimize losses through heating or other handling ofexpensive and sensitive vitamin ingredients.

While the sugar solution and steam are co-sprayed from a single nozzle10 or 80, the enrober 100 can be provided with a plurality of suchnozzles 10 and 80. For example, a first bank or array of two nozzles 10or 80 can be positioned within drum 102 near the inlet end and a secondbank of two nozzles 10 or 80 can be mounted within drum 102 near thedischarge end of enrober 100. Also, intermediate banks of nozzles 10 or80 can be mounted within enrober 100.

The sugar slurry is preferably supplied to the nozzle 10 or 80 as a hotsolution ranging from 250° to 270° F. (121° to 132° C.), preferablyabout 255° to 265° F. (124° to 130° C.) so as to maximize dissolution ofany sugar crystals which can adversely affect the finished productsappearance.

The steam can be either wet, dry or even superheated steam ranging fromabout 4 to 70 psig (24 to 420 KPa), preferably about 10 to 50 psig (60to 300 KPa). The amount of steam consumed is not large and a widevariety of steam consumption rates per pound of sugar solution areuseful.

The food product piece can be any food substrate typically enrobed orpartially coated with a sugar solution. Especially useful as the foodsubstrate are R-T-E cereals, whether flakes, puffed pieces, biscuits,shreds and mixtures thereof. The amount of sugar slurry applied to thefood base can range broadly from about 1 to 150:100, preferably about 50to 120:100.

In another variation, particulate matter can be added to enrober 100 foradhering the particulate matter to the external surface of the R-T-Ecereal pieces. Particulate matter can include fruit pieces, granola,seed bits, candy bits, bran and mixtures thereof. The particulatematerial upon finish drying of the R-T-E cereal adheres to the externalsurface due to the coating action of the sugar slurry.

Alternately or in addition to nozzles 10 and 80, nozzles 116 can beutilized to spray atomized water onto the cylindrical internal surfaceof drum 102. In its method aspect, the present invention broadly residesin providing a thin film of water acting as a renewable surface barrierbetween the product and the cylindrical internal surface of drum 102.Specifically, it has been found that water applied by nozzles 116 atrates in the range of 0.6 to 1.0 gallons (2.25 to 3.785 liters) per hourwhich equated to less than one-half of one percent of the rate at whichthe topical coating slurry was applied was effective in keeping drum 102clean and in fighting build-up problems. The results of the use ofnozzles 116 according to the present invention have been greater thanwhat was expected. Specifically, at present, run times are 10 times aslong when utilizing nozzles 116 than without nozzles 116. For example,in the past, enrobers 100 were shut down for cleaning at least onceevery shift. With nozzles 116 of the present invention, enrobers 100 arerun from three to four days at a stretch. Even when cleaning after threeor four days, drums 102 have only one-tenth the build-up as they hadafter only a single shift without nozzles 116 of the present invention.It was also found that by reducing the water flow, a thin build-up canbe maintained if desired on the cylindrical inner surface of drum 102 toenhance tumbling in sections of drum 102 not including lifters 110. Itis also important to avoid excessive water addition and to avoidspraying water from nozzles 116 onto the product bed for the reason thatexcessive moisture will cause the puffed products to shrink, perhaps asmuch as to their original unpuffed size.

According to the most preferred teachings of the present invention,plastic, hydrophobic drums 102 are utilized in enrobers 100 to provide afirst defense in preventing build-up on the cylindrical internal surfaceof drum 102. If build-up problems continue to exist, such as the resultof applying particulates as a topical coating, and/or if conventionalstainless steel drums 102 are utilized, additional moisture can beprovided to enrober 100 utilizing nozzles 10 or 80 and/or nozzles 116according to the preferred teachings of the present invention.

The sugar slurry can employ conventional sugar coating compositionscontaining about 80% to 90% sugar(s) and the balance moisture. Somesugar coating compositions optionally additionally include modest levelsof an edible oil (e.g., 0.1% to 8%). The sugar slurry can also includecolorants, vitamins and other conventional additives. The sugar coatingcan be supplied at a pressure ranging from about 50 to 150 psig (300 to900 KPa).

However, another dramatic improvement according to the present inventionresides in the sugar slurry that can be used. In conventional sugarcoating compositions, the slurry had a 17% moisture content. This addedmoisture is then removed in the subsequent drying step. With the presentinvention, the moisture content of the slurry can be reduced to about10%. This has effectively resulted in an increase in dryer capacity ofabout 40% since the moisture addition has been reduced by 40%. Dryercapacity has been the traditional bottleneck in processing operations.Also, a typical dryer requires a considerable capital expenditure. Thus,for the minimal capital expenditure required for the present invention,the capital expenditure required for dryers is substantially reduced,with dryers having increased throughput.

The benefits of reduced moisture slurry are especially useful in thesummertime when the ambient air contains high absolute humidity. Duringthese conditions, larger volumes of air must pass through the dryer toremove the same quantity of moisture, due to the air's reduced abilityto pick up additional moisture. Heating these larger air volumesconsumes substantially more energy and can result in reduced productionrates if sufficient energy transfer can not be accomplished by thedryer.

By using lower moisture slurry, less water is introduced into the dryer,and hence less needs to be removed, thereby reducing the dryer energydemand while maintaining normal production rates. This saves energycost, and reduces the need for higher capital expenditures for largerdryers to handle summertime conditions.

Without the present invention, use of low moisture slurry (10% moisture)is impossible because it leads to severe fouling of enrober 100 in about20 to 30 minutes, even under the best operating conditions.

Surprisingly, even low moisture solutions, e.g., 3% to 10% moisture, mayalso be employed. Of course, this would result in near tripling of dryercapacity. It is believed that nozzles 10 and 80 are especially helpfulfor applying the super concentrated slurry as the steam helps tosplatter the slurry onto the product bed.

Thus since the invention disclosed herein may be embodied in otherspecific forms without departing from the spirit or generalcharacteristics thereof, some of which forms have been indicated, theembodiments described herein are to be considered in all respectsillustrative and not restrictive. The scope of the invention is to beindicated by the appended claims, rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

We claim:
 1. Method of applying a topical coating to an exterior surface of multiple pieces of a food base, comprising the steps of: delivering a quantity of the food base to a tumbling vessel; dispensing the topical coating onto the food base in the tumbling vessel, wherein the dispensing step comprises the step of dispensing the topical coating as a slurry in the form of a water-based solution; providing moisture in addition to the topical coating in the tumbling vessel; and tumbling the food base in the tumbling vessel simultaneously as the topical coating is being dispensed and as the moisture is being provided to form a topically coated food base; wherein the delivering step comprises the step of delivering the quantity of the food base to a thin-walled, generally cylindrical tumbling vessel having a continuous, generally cylindrical internal surface formed of hydrophobic material in the form of high-density polyethylene having a low coefficient of friction obtaining a low-stick characteristic with the topically coated food base.
 2. Method of applying a topical coating to an exterior surface of multiple pieces of a food base, including the steps of: delivering a quantity of the food base as a bed on a continuous inner surface of a tumbling vessel, dispensing the topical coating onto the food base in the tumbling vessel, providing moisture in addition to the topical coating in the tumbling vessel, and rotating the tumbling vessel to tumble the food base in the tumbling vessel simultaneously as the topical coating is being dispensed and as the moisture is being provided, wherein the providing step comprises the step of providing the moisture as a thin film of water onto the continuous inner surface of the tumbling vessel above the bed, with the thin film of water acting as a renewable barrier between the continuous inner surface and the bed to keep the continuous inner surface of the tumbling vessel clean and to fight build-up problems.
 3. The method of claim 2 wherein the providing step comprises the step of spraying the moisture onto the continuous inner surface of the tumbling vessel.
 4. The method of claim 3 wherein the spraying step comprises the step of spraying steam.
 5. The method of claim 3 wherein the spraying step comprises the step of spraying air atomized water.
 6. The method of claim 2 wherein the delivering step comprises the step of delivering the quantity of the food base to a thin-walled, generally cylindrical tumbling vessel having a continuous, generally cylindrical internal surface formed of hydrophobic material in the form of high-density polyethylene having a low coefficient of friction obtaining a low-stick characteristic with the topically coated food base.
 7. The method of claim 6 wherein the delivering step comprises the step of delivering the quantity of the food base to the tumbling vessel including a plurality of circumferentially spaced arcuate portions interconnected by lifters, with each of the arcuate portions including a leading edge and a trailing edge circumferentially spaced from and parallel to the leading edge and each of the lifters including a first edge and a second edge circumferentially spaced from and parallel to the first edge, with the first edges being connected to the trailing edges and the second edges being connected to the leading edges, with the leading edges proceeding the trailing edges, with the circumferential spacing between the leading edge and the trailing edge being substantially larger than the circumferential spacing between the first edge and the second edge.
 8. The method of claim 6 wherein the delivering step comprises the step of delivering the quantity of the food base to the tumbling vessel wherein the lifters each include a first leg having the first edge and a third edge circumferentially spaced from and parallel to the first edge and a second leg having a fourth edge integrally connected to the third edge and the second edge circumferentially spaced from and parallel to the fourth edge, with the width between the first edge and the third edge being less than approximately one-half of the width between the fourth edge and the second edge.
 9. The method of claim 2, 3 or 6 additionally comprising the step of: finish drying the topically coated food base to a final moisture content of about 2% to 6%.
 10. The method of claim 2 additionally comprising the step of admixing a quantity of particulate material to the tumbling vessel to adhere the particulate material to the food base.
 11. The method of claim 10 wherein the particulate material comprises fruit pieces, seed pieces, bran, hard candy pieces, granola and mixtures thereof.
 12. Apparatus for applying a topical coating to an exterior surface of multiple pieces of a food base, comprising, in combination: a vessel for tumbling a quantity of the food base, with the vessel including an inlet and a discharge end; means for dispensing the topical coating onto the food base in the vessel, wherein the dispensing means dispenses the topical coating as a slurry in the form of a water-based solution; and means for providing moisture in addition to the topical coating in the vessel, with the topical coating being dispensed and the moisture being provided as the food base is tumbled in the vessel to form a topically coated food base; wherein the vessel is thin-walled and generally cylindrically shaped having a continuous, generally cylindrical internal surface formed of hydrophobic material in the form of high-density polyethylene having a low coefficient of friction obtaining a low-stick characteristic with the topically coated food base.
 13. The apparatus of claim 12 wherein the vessel includes a plurality of circumferentially spaced arcuate portions interconnected by lifters, with each of the arcuate portions including a leading edge and a trailing edge circumferentially spaced from and parallel to the leading edge and each of the lifters (110) including a first edge and a second edge circumferentially spaced from and parallel to the first edge, with the first edges being connected to the trailing edges and the second edges being connected to the leading edges, with the leading edges proceeding the trailing edges, with the circumferential spacing between the leading edge and the trailing edge being substantially larger than the circumferential spacing between the first edge and the second edge.
 14. Apparatus for applying a topical coating to an exterior surface of multiple pieces of a food base, comprising, in combination: a vessel for tumbling a quantity of the food base, with the vessel including an inlet and a discharge end, with the quantity of the food base being held as a bed on a continuous inner surface of the vessel, with the quantity of food base being tumbled by rotating the continuous inner surface; means for dispensing the topical coating onto the food base in the vessel; and means for providing moisture in addition to the topical coating in the vessel, with the topical coating being dispensed and the moisture being provided as the food base is tumbled in the vessel, wherein the providing means comprises means for providing the moisture as a thin film of water onto the continuous inner surface of the vessel above the bed, with the thin film of water acting as a renewable barrier between the continuous inner surface and the bed to keep the continuous inner surface of the vessel clean and to fight build-up problems.
 15. The apparatus of claim 14 wherein the providing means comprises means for spraying the moisture onto the continuous inner surface of the tumbling vessel.
 16. The apparatus of claim 15 wherein the spraying means comprises means for spraying steam.
 17. The apparatus of claim 15 wherein the spraying means comprises means for spraying air atomized water.
 18. The apparatus of claim 14 wherein the vessel is thin-walled and generally cylindrically shaped having a continuous, generally cylindrical internal surface formed of hydrophobic material in the form of high-density polyethylene having a low coefficient of friction obtaining a low-stick characteristic with the topically coated food base.
 19. The apparatus of claim 18 wherein the vessel includes a plurality of circumferentially spaced arcuate portions interconnected by lifters, with each of the arcuate portions including a leading edge and a trailing edge circumferentially spaced from and parallel to the leading edge and each of the lifters including a first edge and a second edge circumferentially spaced from and parallel to the first edge, with the first edges being connected to the trailing edges and the second edges being connected to the leading edges, with the leading edges proceeding the trailing edges, with the circumferential spacing between the leading edge and the trailing edge being substantially larger than the circumferential spacing between the first edge and the second edge.
 20. The apparatus of claim 19 wherein the lifters each include a first leg having the first edge and a third edge circumferentially spaced from and parallel to the first edge and a second leg having a fourth edge integrally connected to the third edge and the second edge circumferentially spaced from and parallel to the fourth edge, with the width between the first edge and the third edge being less than approximately one-half of the width between the fourth edge and the second edge.
 21. Apparatus for applying a topical coating to an exterior surface of multiple pieces of a food base comprising, in combination: a vessel for tumbling a quantity of the food base, with the vessel including an inlet and a discharge end; and means for dispensing the topical coating onto the food base in the vessel, with the topical coating being dispensed as the food base is tumbled in the vessel to form a topically coated food base, wherein the vessel is thin-walled and generally cylindrically shaped having a continuous, generally cylindrical internal surface formed of hydrophobic material in the form of high-density polyethylene having a low coefficient of friction obtaining a low-stick characteristic with the topically coated food base.
 22. The apparatus of claim 21 wherein the vessel includes a plurality of circumferentially spaced arcuate portions interconnected by lifters, with each of the arcuate portions including a leading edge and a trailing edge circumferentially spaced from and parallel to the leading edge and each-of the lifters including a first edge and a second edge circumferentially spaced from and parallel to the first edge, with the first edges being connected to the trailing edges and the second edges being connected to the leading edges, with the leading edges proceeding the trailing edges, with the circumferential spacing between the leading edge and the trailing edge being substantially larger than the circumferential spacing between the first edge and the second edge.
 23. The apparatus of claim 22 wherein the lifters each include a first leg having the first edge and a third edge circumferentially spaced from and parallel to the first edge and a second leg having a fourth edge integrally connected to the third edge and the second edge circumferentially spaced from and parallel to the fourth edge, with the width between the first edge and the third edge being less than approximately one-half of the width between the fourth edge and the second edge. 